Somewhat related, so I might as well throw it out there. Way back in ancient history, when Transgo first
made the -3 version of their shift kit for 400s, the very first one I ever installed [complete O/H] locked up
solid in 3rd. After lots of wasted time, it was core shift in one of the pump halves. With all the bolts snug and
the two castings lined up in a case [or with a band, etc.] if you took the slop out in one direction, it locked
up as above. If you went the other way, it was OK.